> Hi Nicolas,
>
> While this doesn't exactly answer your question, I was wondering what
> scheduler you were using on your GFS2 (Note: I have not used this file
> system before) block. You can find this by issuing 'cat /sys/block/<insert
> block device>/queue/scheduler' ?
>
> By default the system uses cfq, which will show up as [cfq] when catting
> the scheduler as I showed above. This is not the most optimal scheduler
> for a webserver. In most cases you'd be better off with deadline or noop.
> Not being familiar with GFS2 myself, I did skim this article, which makes
> me think noop would be the better choice:
>
> http://www.redhat.com/archives/linux-cluster/2010-June/msg00027.html
>
> This could be why you are seeing the processes waiting on I/O.
>
In my case, /sys/block/dm-9/queue/scheduler show : none and
/sys/block/sdb/queue/scheduler shows "noop anticipatory deadline [cfq]".
Since this is a production cluster, I do not want to make changes to it just
now. I will ask advice from RHEL support for setting this.
But that seems logical.
In the meen time, I'd still like to find a tool to know what files are
requeted to the filesystem and what ones are being waited for...
Thanks
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